The only thing _____ can be done is to stop them from going there.
A. that B. which C. what
China takes the leading position _____ space industry.
| A．in | B．at | C．of | D．up |
I spend much money on books _____ I am not rich.
| A．but | B．so | C．even though | D．as if |
—What a nice classroom!
—It _____ every day.
| A．is cleaning | B．has cleaned | C．must clean | D．is cleaned |
I don’t knowwith this problem．It’s too hard．
| A．which to do | B．when to do | C．what to deal | D．how to deal |
My mother is working sothat she can have any time for me．
| A．hard, hard | B．hardly, hardly | C．hardly; hard | D．hard, hardly |